A known image forming apparatus may include an image forming unit and an image scanner. The image scanner is disposed above the image forming unit. For example, an image forming apparatus includes a first casing that houses an image forming unit, and a second casing that houses an image scanner. The second casing is disposed above the first casing. A sheet discharge opening may be between the first casing and the second casing. The image forming apparatus further includes a document cover disposed above the second casing. A first hinge connects the first casing with the second casing. A second hinge connects the second casing with the document cover. The second casing is configured to open or pivot upward, relative to the first casing about the first hinge. The document cover is configured to open or pivot upward, relative to the second casing about the second hinge.
While the second casing is open, a user of the image forming apparatus may further open the document cover. This may cause the document cover to undesirably tip backwards away from the user due to weight imbalance, e.g., the center of gravity of the image forming apparatus shifted backwards. In particular, in a case that the document cover includes an automatic document feeder (“ADF”), the document cover is relatively heavy in weight. If the user opens such heavy document cover while the second casing is open, the image forming apparatus (e.g., the first casing) is more likely to tip backward.
For example, JP-A 2014-235214 discloses an image forming apparatus including a lock mechanism that holds a second casing relative to a first casing when a document cover is open.